When building vehicles on a production assembly line, the rear drum brake assembly of a motor vehicle braking system may be pre-assembled before being attached to the vehicle body and the parking brake cables may be subsequently attached to an internal brake operating lever through an opening in the drum brake back plate with a “quick-attach device on the internal parking brake lever even though direct access to the braking mechanism is precluded. Examples of such quick-attach” devices are well known and are shown, for example, in GB patent 2,328,257 and U.S. Pat. No. 4,753,325 and form no part of the present invention. U.S. Pat. No. 5,311,793 also discloses a different type of drum brake actuator in which the quick-attach device comprises a resilient spring member located in a passage between a pair of cooperating actuating levers acting between adjacent ends of a pair of brake shoes [or the ends of a single generally U-shaped shoe of the form shown in EP patent 0392829] the spring member deflects a cable nipple to a latching position on one of the levers and subsequently ensures that the nipple does not disengage the latching position on this lever.
One problem with such “quick-attach” devices is that there is no way of verifying that the cable is successfully latched to the lever until the vehicle braking system is assembled and the parking brake is actuated. This is particularly so for electrically operated parking brakes. A further problem with electrically operated parking brakes is that the normal cable travel required for assembly purposes is a significant proportion of the total cable travel available during an operational stroke of the actuation mechanism.
The present invention provides a cable operated drum brake which enables the successful connection of the operating cable to the parking brake lever to be verified, and also reduces assembly travel in the cable.